TEM-EELS studies of electrode materials for Li-ion batteries

Feng Wang

Sustainable Energy Technologies Department

Brookhaven National Laboratory

Upton NY 11973

            Lithium ion batteries have become the most popular rechargeable storage devices for portable electronics, and are being intensively investigated for potential use in electrical vehicles and grid storage. Developing new materials for these demanding applications requires a better understanding of how electrode materials function by tracking electrochemical reactions in the electrodes. However, this type of characterization requires high sensitivity to Li and other constituents at relevant spatial and temporal resolution, along with the capability of capturing changes in both electronic and atomic structures. We developed a suite of electron microscopy (TEM-EELS) for determination of physical and chemical changes of high-energy electrodes. The versatility of the new approaches to track the electrochemical reaction in nanoelectrodes will be discussed along with our recent results on a variety of nanoparticle-based systems including conversion electrodes (FeF₂), alloying electrodes (Si) and intercalation electrodes (Li₄Ti₅O₁₂).